Conventionally, an angular rate sensor is known where four oscillators are symmetrically arranged with respect to a predetermined point in a horizontal plane of a substrate, and a sensing electrode is provided for each oscillator, as disclosed in Japanese Published Unexamined Patent Application No. 2000-180174 (which is hereinafter called Patent Document 1). In the angular rate sensor, all adjacent oscillators are driven and oscillated in opposite phase of a circumferential direction centered around the predetermined point, and if an angular rate occurs around an axis perpendicular to the substrate, detecting masses of respective oscillators are displaced in a direction perpendicular to a driving oscillation. A Coriolis signal is taken out by calculating and processing capacitance change between the detecting masses and the oscillators, and by cancelling external acceleration acting on each of the detecting masses in the horizontal plane of the substrate.
However, in a configuration of the angular rate sensor disclosed in Patent Document 1, because a centrifugal force is applied in a detecting axial direction, the centrifugal force has to be cancelled in order to detect an exact angular rate. However, no measures are implemented on this point, and it is difficult to detect the exact angular rate.
Moreover, the angular rate sensor is frequently used by being mounted on a mobile object such as a vehicle, where the angular rate sensor is often mounted on an elastic member such as a dumper in order to remove vibration and the like different from vehicle motion. In such a case, if the dumper becomes deformed, the angular sensor itself vibrates and rotates, which makes it difficult to detect the exact angular rate.